Special purpose microprocessors are often required to execute sequences of instructions very quickly. One means of accomplishing this is to provide the microprocessor with a reduced set of instructions that can individually be implemented with little or no time delay for ancillary operations such as set-up or memory allocation.
Auslander et al., in U.S. Pat. No. 4,589,087, disclose use of a reduced set of computer instructions that facilitates performance of single machine cycle instructions. This technique is used to track carry operations in addition of digital variables and to provide overflow signals for such operations.
Case et al., in U.S. Pat. No. 4,777,588, disclose a high speed register file, for use with a reduced set of computer instructions, that allows efficient register allocation. One or more registers is local (contents inaccessible to procedures not involving that register directly), and one or more registers is non-local and allows access to its contents by other registers. This allows the integrity of a register file to be maintained.